When putting a power cable in the ground, or on the sea floor, it is often practical to add a fibre optic cable in a space between the power cores.
A power cable assembly device, a power cable and a tool is known from SE-C2-530 277, respectively. The known assembly device however suffers from inefficient equalisation of electric potential.
According to DE-A1-195 08 888 A1, the fibre optic cable is put inside a metal tubing placed at two of the power cores with the intention to provide contact between the metal tubing and the outer conductive plastic material of the power core, in order to equalize the electric potential between the power core and the metal tubing.